Chitosan is a high polymer amino cellulose derivative and is capable of forming salts with acids. It is produced by alkaline entacetylation from chitin. The complete entacetylation is difficult, since the alkali enters into the chitin particles only incompletely during the reaction. A practically acetyl-free chitin, namely pure chitosan, can be obtained only through repeated alkali treatment or through fractionation. Commercial chitosan represents therefore a more or less entacetylated product with a chitosan portion from about 70 to 90% by weight.
The corresponding salts can be obtained by neutralization of the free amino groups of the chitosan with acids. Acids which provide the water-soluble salts of chitosan are, for example, hydrochloric acid, formic acid, acetic acid, lactic acid or other low molecular inorganic or organic acids.
The water-soluble salts of chitosan are used as additives in the paper and textile industries, as coagulants for suspensions and as chelating agents for heavy metals. In addition, several medicinal uses for water-soluble chitosan salts are known, for example as described in the book "Chitin" by Muzarelli, Pergamon Press, Oxford, 1977. Finally, the use of water-soluble chitosan salts, particularly since they have the character of cationic resins, as strengthening and conditioning components of hair treatment preparations, is known in the field of cosmetics. For example, their use in preparations for the strengthening of hairdos is known from German patent No. 2,627,419, whereas German Offenlegungsschrift No. 2,754,796 describes their employment in hair treatment and hair washing preparations. In aqueous or aqueous-alcoholic solutions of chitosan with the mentioned acids, there forms, however, in the presence of typical anionic tensides, such as e.g. alkylsulfates, alkylethersulfates, alkylsulfonates, alkylarylsulfonates, alkylsulfosuccinates and the alkali salts of long-chain fatty acids, insoluble chitosan salts. The valuable characteristics of chitosan can therefore not be utilized for preparations based upon such anionic tensides, such as for example textile and household cleaning preparations, personal hygiene (body) cleaning preparations, shampoos or hair conditioning preparations.